COMBOSOLAR datasheet(47/57 Pages) TI1

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AFE031

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SBOS531D – AUGUST 2010 – REVISED MAY 2012

Figure 53. Heat Flow in the QFN Package

The exposed thermal pad must be soldered to the PCB thermal pad. The thermal pad on the PCB should be the

same size as the exposed thermal pad on the underside of the QFN package. Refer to Application Report,

QFN/SON PCB Attachment, literature number SLUA271A, for recommendations on attaching the thermal pad to

the PCB. Figure 54 illustrates the direction of heat spreading into the PCB from the device.

Figure 54. Heat Spreading into PCB

The heat spreading into the PCB is maximized if the thermal path is uninterrupted. Best results are achieved if

the heat-spreading surfaces are filled with copper to the greatest extent possible, maximizing the percent area

covered on each layer. As an example, a thermally robust, multilayer PCB design may consist of four layers with

copper (Cu) coverage of 60% in the top layer, 85% and 90% in the inner layers, respectively, and 95% on the

bottom layer.

Product Folder Link(s): AFE031

COMBOSOLAR Datasheet(PDF) 47 Page - Texas Instruments